The present invention is directed to the field of obtaining blood samples from a living patient and more particularly to apparatus suitable for use with conventional blood receptacle assemblies and double-ended needles.
Various devices and methods have been developed for withdrawing blood from a patient. FIG. 1 shows one such blood receptacle assembly A, along with a first embodiment of the present invention to be described below. Assembly A includes two parts: blood collecting assembly B and blood sampling tube C. Tube C is a standard blood sampling tube, and has a rubber stopper D in the opening E of tube C. Blood collecting assembly B includes a first housing F including a hollow needle G. Housing F is attached by flexible tubing H to a second housing I having a second needle J. First needle G punctures the skin and underlying vein of the patient (not shown). Rubber stopper D is inserted into housing I so that second needle J extends through stopper D into the tube C. (As shown in FIG. 1, tube C is in a retracted position relative to housing I in which needle J does not penetrate stopper D). One such device for withdrawing blood is known as a "VACUTAINER," and is available from Becton-Dickenson, although others are also available.
In use, blood travels from the patient to the tube C via needle G, flexible tubing H, and needle J. Often, more than one sample of blood is required, each sample being placed in a separate blood sampling tube C which may contain one of a variety of preparations to facilitate a particular analytical procedure. Such preparations may include, for example, preservatives, anti-coagulants, and the like.
Using conventional blood sampling devices, a venipuncturist must stabilize the first needle puncturing the vein while simultaneously manipulating the blood sampling tube or tubes into the housing and into engagement with the second needle. Occasionally, the process of engaging blood sampling tube C with second needle J causes first needle G, in contact with the patient's vein, to inadvertently dislodge or puncture the other side of the patient's vein. In addition to increasing the painfulness of the procedure and possibly contributing to hematoma formation, dislodging the needle or puncturing the other side of the vein may necessitate re-sticking the patient. To ensure sterility, re-sticking the patient requires the use of a new blood receptacle assembly, therefore increasing the initial cost the blood drawing procedure. Additionally, many patients who undergo multiple blood drawings have poor veins, increasing the difficulty of finding a suitable vein to use for blood sampling.
There is therefore a need for an improved blood sampling device which will permit blood samples to be taken with a conventional blood receptacle assembly, such as a "VACUTAINER," while providing increased stability, ease of use, safety and convenience for the blood drawing procedure. Further, there is a need for automating the blood taking procedure to permit multiple blood samples to be taken from a patient with increased stability, safety and convenience.